Download - Chapter 4
Chapter 4Chapter 4
The Tissue Level The Tissue Level
of Organizationof Organization
Tissues are a group of cells with a common Tissues are a group of cells with a common embryonic origin that function together to embryonic origin that function together to carry out specialized activities.carry out specialized activities.
TissuesTissues
Histology is the study of the Histology is the study of the microscopic anatomy of cells and microscopic anatomy of cells and tissues – it is a branch of pathology.tissues – it is a branch of pathology.
TissuesTissues
Tissues are formed Tissues are formed
by grouping cells by grouping cells
together using a together using a
variety of variety of
Intercellular Intercellular
Junctions .Junctions .
Intracellular JunctionsIntracellular Junctions
Tight JunctionsTight Junctions are found where a are found where a
leakproof seal is needed between leakproof seal is needed between
cells.cells.
Intracellular Intracellular JunctionsJunctions
Adherens JunctionsAdherens Junctions make an adhesion belt (like make an adhesion belt (like
the belt on your pants) that keeps tissues from the belt on your pants) that keeps tissues from
separating as they stretch and contract.separating as they stretch and contract.
Cadherin is a glycoprotein Cadherin is a glycoprotein
that forms the belt-like that forms the belt-like
““plaque”.plaque”.
Intracellular JunctionsIntracellular Junctions
DesmosomesDesmosomes act as “spot welds”. act as “spot welds”. They also use cadherin glycoprotein They also use cadherin glycoprotein (plus intermediate filaments) to hook (plus intermediate filaments) to hook into the cytoplasm.into the cytoplasm.
Intracellular JunctionsIntracellular Junctions
HemidesmosomesHemidesmosomes are half-welds that join are half-welds that join cells to the basement membrane.cells to the basement membrane.
Intracellular Intracellular JunctionsJunctions
Gap JunctionsGap Junctions are are pores (connexons) that pores (connexons) that allow small substances allow small substances like ions to pass like ions to pass between cells. If one between cells. If one of the cells gets sick or of the cells gets sick or dies, these seal like a dies, these seal like a hatch to prevent hatch to prevent damage to other cells.damage to other cells.
Intracellular JunctionsIntracellular Junctions
Of all the cells in the body, they combine Of all the cells in the body, they combine to make only 4 basic tissue types:to make only 4 basic tissue types: Epithelial tissuesEpithelial tissues Connective tissuesConnective tissues Muscular tissuesMuscular tissues Nervous tissuesNervous tissues
The 4 Basic TissuesThe 4 Basic Tissues
Epithelial tissuesEpithelial tissues cover body surfaces and form cover body surfaces and form
glands and line hollow organs, body cavities, and glands and line hollow organs, body cavities, and
ducts.ducts.
The 4 Basic TissuesThe 4 Basic Tissues
Connective tissues (C.T.)Connective tissues (C.T.) protect, protect, support, and bind organs.support, and bind organs. Fat is a type of C.T. that stores energy.Fat is a type of C.T. that stores energy. Red blood cells, white blood cells, and Red blood cells, white blood cells, and
platelets are all C.T.platelets are all C.T.
The 4 Basic TissuesThe 4 Basic Tissues
Muscular tissuesMuscular tissues generate the generate the physical force needed to make body physical force needed to make body structures move. They also generate structures move. They also generate heat used by the body.heat used by the body.
Nervous tissuesNervous tissues detect changes in detect changes in the body and respond by generating the body and respond by generating nerve impulses.nerve impulses.
The 4 Basic TissuesThe 4 Basic Tissues
Tissues of the body develop from three primary germ Tissues of the body develop from three primary germ
layers: layers: Endoderm, Mesoderm, and EctodermEndoderm, Mesoderm, and Ectoderm
Epithelial tissues from Epithelial tissues from
all three germ layersall three germ layers
C.T. and muscle are C.T. and muscle are
derived from mesoderm.derived from mesoderm.
Nervous tissue Nervous tissue
develops from develops from
ectoderm.ectoderm.
The 4 Basic TissuesThe 4 Basic Tissues
EpitheliuEpitheliumm Epithelium is used to line surfaces Epithelium is used to line surfaces
and form protective barriers. and form protective barriers. Epithelium is also good at secreting Epithelium is also good at secreting things like mucous, hormones, andthings like mucous, hormones, and
other substances .other substances . All epithelia have a All epithelia have a
free apical surface free apical surface
and an attached and an attached
basal surface.basal surface.
The basal layer of the epithelium The basal layer of the epithelium secretes a basal lamina; the secretes a basal lamina; the underlying C.T. secretes a reticular underlying C.T. secretes a reticular lamina.lamina. Together the basal Together the basal
lamina and the reticular lamina and the reticular
lamina form a non-lamina form a non-
cellular basement cellular basement
membrane on which membrane on which
the epithelium sits.the epithelium sits.
EpitheliumEpithelium
Epithelia are Epithelia are namednamed according to the according to the shape of their cells, and the thickness or shape of their cells, and the thickness or arrangement of their layers (of cells).arrangement of their layers (of cells).
EpitheliuEpitheliumm
EpitheliumEpithelium
Naming epithelia according to Naming epithelia according to shapeshapeEpitheliumEpithelium
Flat, wide “paving stone” cells
Cells as tall as they are wide
Cells taller than they are wide
One layer. All cells in contact with
basement membrane
Appears to have layers, but in reality all cells go
from the apex to the base
Two or more layers. Only basal layer in
contact with basement membrane
Naming epithelia according to Naming epithelia according to arrangementarrangementEpitheliumEpithelium
Naming epithelia Naming epithelia Three different cell shapes Three different cell shapes xx three different three different
cell arrangements = nine possibilities. Two cell arrangements = nine possibilities. Two of these are not used. Add transitional (cells of these are not used. Add transitional (cells that change shape), and we’re back up to that change shape), and we’re back up to eight possible combinations.eight possible combinations.
If different shapes are present in layers of If different shapes are present in layers of cells, the epithelium is always named by the cells, the epithelium is always named by the shape of cells in the apical (outermost) layer.shape of cells in the apical (outermost) layer.
EpitheliumEpithelium
simple squamous
pseudostratified squamous
stratified squamous
simple cuboidalpseudostratified
cuboidalstratified cuboidal
simple columnarpseudostratified
columnarstratified columnar
transitional
Simple Squamous EpitheliumSimple Squamous Epithelium is is composed of a single layer of flat cells composed of a single layer of flat cells found:found: In the air sacs of lungsIn the air sacs of lungs In the lining of blood In the lining of blood
vessels, the heart, and lymphatic vesselsvessels, the heart, and lymphatic vessels In all capillaries, including those of the kidneyIn all capillaries, including those of the kidney As the major part of a As the major part of a
serous membraneserous membrane
EpitheliumEpithelium
Simple Cuboidal EpitheliumSimple Cuboidal Epithelium is is composed of a single layer of cube composed of a single layer of cube shaped cells.shaped cells. It is often found liningIt is often found lining
the tubules of the the tubules of the
kidneys and manykidneys and many
other glands.other glands.
EpitheliumEpithelium
simple squamouspseudostratified
squamousstratified squamous
simple cuboidal
pseudostratified cuboidal
stratified cuboidal
simple columnarpseudostratified
columnarstratified columnar
transitional
Simple Columnar EpitheliumSimple Columnar Epithelium forms forms a single layer of column-like cells, ± a single layer of column-like cells, ± cilia, ± microvilli, ± mucous (goblet cilia, ± microvilli, ± mucous (goblet cells).cells). Goblet cells are simple Goblet cells are simple
columnar cells that columnar cells that
have differentiated to have differentiated to
acquire the ability to acquire the ability to
secrete mucous.secrete mucous.
EpitheliumEpithelium
simple squamouspseudostratified
squamousstratified squamous
simple cuboidal pseudostratified cuboidal
stratified cuboidal
simple columnar
pseudostratified columnar
stratified columnar
transitional
Pseudostratified Columnar EpitheliumPseudostratified Columnar Epithelium appears appears
to have layers, due to nuclei which are at various to have layers, due to nuclei which are at various
depths. In reality, all cells are attached to the depths. In reality, all cells are attached to the
basement basement
membrane in a single membrane in a single
layer, but some do not layer, but some do not
extend to the apical surface.extend to the apical surface.
simple squamouspseudostratified
squamousstratified squamous
simple cuboidal pseudostratified cuboidal stratified cuboidal
simple columnarpseudostratified
columnarstratified columnar
transitional
EpitheliumEpithelium
Stratified Squamous EpitheliumStratified Squamous Epithelium has an apical has an apical
surface that is made up of squamous (flat) cells.surface that is made up of squamous (flat) cells.
The other layers have different The other layers have different
shapes, but the name is based shapes, but the name is based
on the apical layer.on the apical layer.
The many layers are ideal forThe many layers are ideal for
protection againstprotection against
strong frictionstrong friction
forces.forces.
simple squamouspseudostratified
squamousstratified
squamous
simple cuboidalpseudostratified
cuboidalstratified cuboidal
simple columnarpseudostratified
columnarstratified columnar
transitional
EpitheliuEpitheliumm
Stratified Cuboidal EpitheliumStratified Cuboidal Epithelium has has an apical surface made up of two or an apical surface made up of two or more layers of cube-shaped cells.more layers of cube-shaped cells. Locations include the sweatLocations include the sweat
glands and part of the glands and part of the
♂ ♂ urethraurethra Stratified Columnar EpitheliumStratified Columnar Epithelium is is
very rare, and for very rare, and for ourour
purposes, hardly purposes, hardly
worth mentioning.worth mentioning.
EpitheliumEpithelium
simple squamouspseudostratified
squamousstratified squamous
simple cuboidalpseudostratified
cuboidalstratified cuboidal
simple columnarpseudostratified
columnarstratified columnar
transitional
simple squamouspseudostratified
squamousstratified squamous
simple cuboidalpseudostratified
cuboidalstratified cuboidal
simple columnarpseudostratified
columnarstratified columnar
transitional
The cells of The cells of Transitional EpitheliumTransitional Epithelium change change shape depending on the state of stretch in the shape depending on the state of stretch in the tissue.tissue.
EpitheliumEpithelium
Simple squamous makes up epithelial membranes and Simple squamous makes up epithelial membranes and
lines the blood vessels.lines the blood vessels.
Columnar is common in the digestive tract.Columnar is common in the digestive tract.
Pseudostratified ciliated Pseudostratified ciliated
columnar is characteristic columnar is characteristic
of the upper respiratory tract.of the upper respiratory tract.
Transitional is found in Transitional is found in
the bladder.the bladder.
Cuboidal lines ducts and Cuboidal lines ducts and
sweat glands.sweat glands.
EpitheliumEpithelium
Connective Tissues are the most abundant Connective Tissues are the most abundant
and widely distributed tissues in the body. and widely distributed tissues in the body.
They perform numerous functions:They perform numerous functions:• Bind tissues togetherBind tissues together
• Support and strengthen tissueSupport and strengthen tissue
• Protect and insulate internal organsProtect and insulate internal organs
• Compartmentalize and transportCompartmentalize and transport
• Energy reserves and immune responsesEnergy reserves and immune responses
Connective TissueConnective Tissue
Collagen is the main protein of C.T. and the Collagen is the main protein of C.T. and the
most abundant protein in the body, making most abundant protein in the body, making
up about 25% of total protein content.up about 25% of total protein content.
Connective tissue is usuallyConnective tissue is usually
highly vascular and suppliedhighly vascular and supplied
with many nerves.with many nerves.
The exception is cartilage and The exception is cartilage and
tendon - both have little or no tendon - both have little or no
blood supply and no nerves.blood supply and no nerves.
Connective TissuesConnective Tissues
Although they are a varied group, all C.T. Although they are a varied group, all C.T.
share a common “theme”:share a common “theme”: Sparse cellsSparse cells
Surrounded by an Surrounded by an extracellular matrixextracellular matrix
The extracellular matrix is a non-cellular The extracellular matrix is a non-cellular
material located between and around the material located between and around the
cells.cells. It consists of It consists of protein fibers protein fibers and and ground ground
substance substance (the ground substance may be fluid, (the ground substance may be fluid,
semifluid, gelatinous, or calcified.)semifluid, gelatinous, or calcified.)
Connective TissuesConnective Tissues
Common C.T. cellsCommon C.T. cells FibroblastsFibroblasts are the most numerous are the most numerous
cell of connective tissues. These cells cell of connective tissues. These cells secrete protein fibers (collagen, secrete protein fibers (collagen, elastin, & reticular elastin, & reticular
fibers) and afibers) and a
““ground substance”ground substance”
which varies from which varies from
one C.T. to another.one C.T. to another.
Cells Of Connective TissuesCells Of Connective Tissues
Of the other common C.T. cells:Of the other common C.T. cells: Chondrocytes Chondrocytes make the various cartilaginous C.T.make the various cartilaginous C.T.
AdipocytesAdipocytes store triglycerides. store triglycerides.
OsteocytesOsteocytes make bone. make bone.
White blood cells White blood cells are part of the blood.are part of the blood.
Cells of Connective TissuesCells of Connective Tissues
C.T. cells secrete 3 common fibers:C.T. cells secrete 3 common fibers: Collagen fibersCollagen fibers
Elastin fibersElastin fibers
Reticular fibersReticular fibers
Connective TissuesConnective Tissues
This graphic represents a collage of This graphic represents a collage of different C.T. elements (cells and different C.T. elements (cells and fibers) and not a specific C.T.fibers) and not a specific C.T.
Connective TissuesConnective Tissues
Embryonic connective tissueEmbryonic connective tissue MesenchymeMesenchyme Mucous connective tissueMucous connective tissue
Mature connective tissueMature connective tissue Loose connective tissueLoose connective tissue Dense connective tissueDense connective tissue CartilageCartilage BoneBone LiquidLiquid
Connective Tissue Connective Tissue ClassificationClassification
There are 2 Embryonic Connective There are 2 Embryonic Connective Tissues:Tissues: MesenchymeMesenchyme gives rise to all other connective gives rise to all other connective
tissues.tissues. Mucous C.T. Mucous C.T. (Wharton's Jelly) is a gelatinous (Wharton's Jelly) is a gelatinous
substance within the umbilical cord and is a substance within the umbilical cord and is a rich source of stem cells.rich source of stem cells.
Embryonic Connective Embryonic Connective TissuesTissues
Loose Connective TissuesLoose Connective Tissues
Areolar Connective Tissue Areolar Connective Tissue is the most is the most
widely distributed in the body. It contains widely distributed in the body. It contains
several types of cells and all three fiber several types of cells and all three fiber
types.types.
AdiposeAdipose
ReticularReticular
Mature Connective Mature Connective TissuesTissues
Loose Connective TissuesLoose Connective Tissues
Loose areolarLoose areolar
Adipose tissue Adipose tissue is located in the is located in the
subcutaneous layer deep to the skin and subcutaneous layer deep to the skin and
around organs and joints.around organs and joints.
ReticularReticular
Mature Connective Mature Connective TissuesTissues
Loose Connective TissuesLoose Connective Tissues
Loose areolarLoose areolar
AdiposeAdipose
Reticular connective tissue Reticular connective tissue is a is a
network of interlacing reticular fibers and network of interlacing reticular fibers and
cells.cells.
Mature Connective Mature Connective TissuesTissues
Dense Connective TissuesDense Connective Tissues
Dense Irregular Connective Tissue Dense Irregular Connective Tissue
consists predominantly of fibroblasts and consists predominantly of fibroblasts and
collagen fibers randomly arranged.collagen fibers randomly arranged.
Dense regularDense regular
ElasticElastic
Mature Connective TissuesMature Connective Tissues
Dense Connective TissuesDense Connective Tissues
Dense IrregularDense Irregular
Dense regular Connective Tissue Dense regular Connective Tissue comprise comprise
tendons, ligaments, and other strong tendons, ligaments, and other strong
attachments where the need for strength along attachments where the need for strength along
one axis is mandatory (a muscle pulling on a one axis is mandatory (a muscle pulling on a
bone).bone).
ElasticElastic
Mature Connective Mature Connective TissuesTissues
Dense Connective TissuesDense Connective Tissues
Dense IrregularDense Irregular
Dense regularDense regular
Elastic Connective Tissue Elastic Connective Tissue consists consists
predominantly of fibroblasts and freely predominantly of fibroblasts and freely
branching elastic fibers.branching elastic fibers.
Mature Connective Mature Connective TissuesTissues
Cartilage Cartilage is a tissue with poor blood is a tissue with poor blood
supply that grows slowly. When injured supply that grows slowly. When injured
or inflamed, repair is slow.or inflamed, repair is slow. Hyaline cartilage Hyaline cartilage is the most abundant is the most abundant
type of cartilage; it covers the ends of long type of cartilage; it covers the ends of long
bones and parts of the ribs, nose, trachea, bones and parts of the ribs, nose, trachea,
bronchi, and larynx.bronchi, and larynx.
FibrocartilageFibrocartilage
Elastic cartilageElastic cartilage
Mature Connective TissuesMature Connective Tissues
CartilageCartilage
Hyaline cartilageHyaline cartilage
Fibrocartilage, Fibrocartilage, with its thick bundles of with its thick bundles of
collagen fibers, is a very strong, tough collagen fibers, is a very strong, tough
cartilage.cartilage.
Elastic cartilageElastic cartilage
Mature Connective Mature Connective TissuesTissues
CartilageCartilage
Hyaline cartilageHyaline cartilage
FibrocartilageFibrocartilage
Elastic cartilage Elastic cartilage consists of consists of
chondrocytes located in a threadlike chondrocytes located in a threadlike
network of elastic fibers. network of elastic fibers.
Mature Connective TissuesMature Connective Tissues
BoneBone is a connective tissue with a calcified is a connective tissue with a calcified
intracellular matrix. In the right circumstances, intracellular matrix. In the right circumstances,
the chondrocytes of cartilage are capable of the chondrocytes of cartilage are capable of
turning into the osteocytes that make up bone turning into the osteocytes that make up bone
tissue.tissue.
We will study bone in detail in Chapter 6.We will study bone in detail in Chapter 6.
Mature Connective TissuesMature Connective Tissues
Blood and lymph Blood and lymph are atypical liquid are atypical liquid connective tissues that we will study in connective tissues that we will study in Chapters 19 and 22. As we have seen, Chapters 19 and 22. As we have seen, blood has many cells. It also has blood has many cells. It also has fibers (such as fibrin that makes blood fibers (such as fibrin that makes blood clot).clot).
Mature Connective TissuesMature Connective Tissues
Summary of Mature Connective Summary of Mature Connective TissuesTissues
Combining two tissues creates an organ. However, Combining two tissues creates an organ. However,
most of the organs and all of the organs systems most of the organs and all of the organs systems
studied this year contain all 4 basic types of tissues.studied this year contain all 4 basic types of tissues.
Epithelial membranes are the simplest organs in Epithelial membranes are the simplest organs in
the body, constructed of the body, constructed of onlyonly epithelium and a epithelium and a
little bit of connective tissue.little bit of connective tissue.
Epithelial MembranesEpithelial Membranes
Epithelial membranes = epithelium + Epithelial membranes = epithelium +
connective tissueconnective tissue Mucous membranesMucous membranes
Serous membranesSerous membranes
Cutaneous membrane = skin Cutaneous membrane = skin
Epithelial MembranesEpithelial Membranes
Mucous membranes line “interior” body surfaces Mucous membranes line “interior” body surfaces
open to the outside:open to the outside:
Digestive tractDigestive tract
Respiratory tractRespiratory tract
Reproductive tractReproductive tract
Serous membranes line some internal surfaces:Serous membranes line some internal surfaces:
Parietal layer next to body wallParietal layer next to body wall
Serous fluid between layersSerous fluid between layers
Visceral layer next to organVisceral layer next to organ
Epithelial MembranesEpithelial Membranes
Skin as a cutaneous membrane is studied in Chapter 5.Skin as a cutaneous membrane is studied in Chapter 5.
Epithelial Epithelial MembranesMembranes
Synovial membranes enclose certain joints Synovial membranes enclose certain joints and are made of and are made of connective tissue only.connective tissue only.
Synovial MembranesSynovial Membranes
Muscles and nerve tissues are the last of the 4 basic Muscles and nerve tissues are the last of the 4 basic
tissue types. Neurons and muscle fibers are considered tissue types. Neurons and muscle fibers are considered
excitable cellsexcitable cells because they exhibit because they exhibit electrical electrical
excitability,excitability, the ability to respond to certain stimuli the ability to respond to certain stimuli
by producing electrical signals such as by producing electrical signals such as action action
potentials.potentials.
Action potentials can propagate (travel) along the Action potentials can propagate (travel) along the
plasma membrane of a neuron or muscle fiber due to plasma membrane of a neuron or muscle fiber due to
the presence of specific voltage-gated ion channels.the presence of specific voltage-gated ion channels.
Each will be studied in depth in upcoming chapters.Each will be studied in depth in upcoming chapters.
Muscle and Nerve TissuesMuscle and Nerve Tissues
Muscle and Nerve Muscle and Nerve TissuesTissues